1. Field of the Invention
The present invention pertains to a method of updating maximum or minimum values of measurement data of various types of physical quantities resulting from sensors or the like and particularly relates to shortening processing time and curtailing data quantities required for updating.
2. Description of the Related Art
Conventionally, in operation control of automobiles such as, for example, fuel injection control, measurement values of various types of physical quantities, such as engine coolant temperature, fuel temperature and the temperature of a diesel particulate filter (hereinafter called “DPF”), are directly and indirectly used.
Incidentally, in automobiles of recent years, electronic control devices for electronically controlling the operation thereof are installed, and there are many electronic control devices configured such that not only operation control for vehicle travel is performed, but also, when some kind of problem arises in the vehicle operation, operation analysis thereof is performed.
For example, sometimes electronic control devices are configured such that, in regard to the engine coolant temperature, the fuel temperature and the DPF temperature discussed above, judgment processing of whether or not abnormal overheating had occurred in the past at respective temperature measurement places is executed by the electronic control device as one operation analysis. For that reason, electronic control devices are configured such that, in regard to these temperatures, for example, at each predetermined period, a maximum temperature within that period is acquired, the electronic control device compares that maximum temperature with a maximum temperature that has been acquired most recently, and when that maximum temperature exceeds the maximum temperature that has been acquired most recently, that maximum temperature is stored in a nonvolatile storage element or the like as a new maximum temperature, so that when the electronic control device executes operation analysis, those stored data are used in judgment processing.
When an electronic control device periodically updates and stores this maximum temperature, a situation where abnormal data caused by a temporary problem in the sensor, such as, for example, a temporary disconnection, a short, or noise, are erroneously used as update values must be avoided as much as possible.
As measures to avoid the acquisition of abnormal data, for example, a technique that uses a so-called mean value of data and a technique that uses a median value of data have conventionally been known as disclosed, for example, in Japanese Paten No. 2,852,059.
Moreover, a technique configured to calculate estimate values of desired physical quantities by arithmetic processing in addition to measurement data and to be able to use those in operation control and the like has been proposed as disclosed, for example, in Japanese Paten No. 3,849,357.
However, in the methods that use a mean value or a median value of measurement values, there are the problems that a large quantity of past data are required, so a large storage area for saving data, or in other words a large-capacity storage element, is required, which not only incurs an increase in the cost of the device but also requires more time for data processing, incurs an increase in the computational load of a microcomputer that performs arithmetic processing, and can affect the processing capability of operation control overall.